Ohmite F40J4K0 Equivalent & Substitute Parts

Part Overview

The Ohmite F40J4K0 is a 4 kOhms ±5% 40W wirewound chassis mount resistor from the Stackohm® 250 series. This component is designed for high-power applications requiring stable resistance values across extended temperature ranges. The part maintains Active product status with 918 units currently in stock. Substitute parts are identified when design requirements allow for increased power dissipation capacity or when inventory constraints necessitate alternative sourcing while maintaining electrical and mechanical compatibility.

Substiute Parts

F40J4K0

OhmiteIn Stock: 1010F40J4K0 Datasheet

Current PartRFQ

F55J4K0

OhmiteIn Stock: 1928F55J4K0 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

The Ohmite F55J4K0 qualifies as a direct substitute for the F40J4K0 based on the following criteria:

Matching Parameters (Substitution Basis):

• Resistance value: 4 kOhms (identical)
• Tolerance: ±5% (identical)
• Temperature coefficient: ±260ppm/°C (identical)
• Operating temperature range: -55°C to 350°C (identical)
• Composition: Wirewound (identical)
• Coating: Vitreous Enamel Coated (identical)
• Mounting feature: Flange Braces, Right Angle (identical)
• Lead style: Solder Lugs (identical)
• Package type: Radial, Flat Oval (identical)
• Series: Stackohm® 250 (identical)

Differing Parameter (Upgrade Characteristic):

• Power rating: 55W (versus 40W in F40J4K0)

The F55J4K0 provides increased power dissipation capacity while maintaining all electrical and mechanical specifications. This substitution is valid for applications where the original 40W rating is sufficient, as the higher-rated component operates within the same electrical parameters.

Parameter Comparison

Engineering Selection Recommendations

Both the F40J4K0 and F55J4K0 maintain Active product status within the Stackohm® 250 series. Selection between these parts depends on application power requirements and available board space.

The F40J4K0 is appropriate for applications with power dissipation requirements up to 40W and where compact form factor is prioritized. The component's 2.000" length accommodates space-constrained designs.

The F55J4K0 is suitable for applications requiring up to 55W power dissipation. The increased length of 4.600" accommodates the higher power rating while maintaining identical height and width dimensions. Both parts share identical compliance classifications (RoHS non-compliant, REACH Unaffected, EAR99 export classification).

Frequently Asked Questions (FAQ)

Q: Can the F55J4K0 replace the F40J4K0 in existing designs?

A: Yes. The F55J4K0 maintains identical electrical parameters (4 kOhms ±5%, ±260ppm/°C, -55°C to 350°C operating range) and mechanical mounting features (Flange Braces, Right Angle, Solder Lugs). The primary difference is increased power rating (55W versus 40W) and physical length (4.600" versus 2.000"). Verify available board space before substitution.

Q: What is the physical size difference between these parts?

A: The F40J4K0 measures 2.000" L × 1.000" W × 0.563" H (seated). The F55J4K0 measures 4.600" L × 1.000" W × 0.563" H (seated). Width and height remain identical; length increases by 1.500" to accommodate the higher power rating.

Q: Are there compliance or regulatory differences between these parts?

A: No. Both parts share identical compliance status: RoHS non-compliant, REACH Unaffected, and EAR99 export classification.

Q: When should the F40J4K0 be used instead of the F55J4K0?

A: Use the F40J4K0 when application power dissipation does not exceed 40W and when board space constraints require the more compact 2.000" length.

Q: Are these parts from the same product series?

A: Yes. Both are members of the Ohmite Stackohm® 250 series, ensuring consistent performance characteristics and manufacturing standards.